Hi Sacha, As Brian noted, you will have to expand the vertical axis. Here is one way to do it.
plot(GDP.per.head, fitted(LinearModel.1),ylim=c(-60,1200)) devlm1<-lm(fitted(LinearModel.1)~GDP.per.head) abline(devlm1) conflm1<-confint(devlm1) abline(coef=conflm1[,1],lty=2) abline(coef=conflm1[,2],lty=2) predict(LinearModel.1, interval = "prediction") library(plotrix) predmat<-predict(LinearModel.1, interval = "prediction") dispersion(GDP.per.head,fitted(LinearModel.1), predmat[,3],predmat[,2],interval=FALSE) You may want to do something about the overlapping points. Jim On Thu, May 7, 2015 at 5:52 AM, David L Carlson <dcarl...@tamu.edu> wrote: > Something like this? > > # Compute the prediction limits and get their range to set ylim= > plim <- predict(LinearModel.1, interval = "prediction") > rnge <- c(min(plim[ , 2]), max(plim[ , 3])) > plot(GDP.per.head, fitted(LinearModel.1),ylim=rnge) > > # As before > devlm1<-lm(fitted(LinearModel.1)~GDP.per.head) > abline(devlm1) > conflm1<-confint(devlm1) > abline(coef=conflm1[,1],lty=2) > abline(coef=conflm1[,2],lty=2) > > # Plot the prediction limits > segments(GDP.per.head, plim[ , 2], GDP.per.head, plim[ , 3], col="gray") > > ------------------------------------- > David L Carlson > Department of Anthropology > Texas A&M University > College Station, TX 77840-4352 > > > -----Original Message----- > From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of Cade, Brian > Sent: Wednesday, May 6, 2015 2:22 PM > To: varin sacha > Cc: R-help Mailing List > Subject: Re: [R] Drawing the regression line and the 95% confidence intervals > > The prediction intervals are likely to be much wider than the confidence > intervals so you will need to be sure you scale the yaxis limits large > enough to see them. > > Brian > > Brian S. Cade, PhD > > U. S. Geological Survey > Fort Collins Science Center > 2150 Centre Ave., Bldg. C > Fort Collins, CO 80526-8818 > > email: ca...@usgs.gov <brian_c...@usgs.gov> > tel: 970 226-9326 > > > On Wed, May 6, 2015 at 12:59 PM, varin sacha <varinsa...@yahoo.fr> wrote: > >> Dear Jim, >> >> I really thank you lots, it perfectly works ! >> The reproducible example is below. >> >> Last thing : I can easily get the predictions intervals but I don't get to >> draw them. >> If I want to draw on the same graph (the one I already have the confidence >> intervals) the prediction intervals. I have tried the abline function >> without success. How can I do ? >> >> GDP.per.head=c(600,560,340,560,580,300,570,900,680,290,590,340) >> Quality.score=c(4.5,6.5,6,4.5,7,3,9,10,12.5,6.5,7,9) >> Competitivness.score=c(1000,1200,1400,700,680,1010,340,560,690,500,690,460) >> LinearModel.1=lm(GDP.per.head ~ Quality.score + Competitivness.score) >> >> plot(GDP.per.head, fitted(LinearModel.1),ylim=c(200,800)) >> devlm1<-lm(fitted(LinearModel.1)~GDP.per.head) >> abline(devlm1) >> conflm1<-confint(devlm1) >> abline(coef=conflm1[,1],lty=2) >> abline(coef=conflm1[,2],lty=2) >> predict(LinearModel.1, interval = "prediction") >> >> Many thanks once more for your help. >> Sacha >> >> >> ----- Mail original ----- >> De : Jim Lemon <drjimle...@gmail.com> >> À : varin sacha <varinsa...@yahoo.fr> >> Cc : R-help Mailing List <r-help@r-project.org> >> Envoyé le : Mercredi 6 mai 2015 1h02 >> Objet : Re: [R] Drawing the regression line and the 95% confidence >> intervals >> >> Hi Sacha, >> The line you have requested is off the plot. The following will >> produce what I think you are asking, but I cannot speak for whether it >> means anything sensible. >> >> plot(GDP.per.head, fitted(LinearModel.1),ylim=c(200,800)) >> devlm1<-lm(fitted(LinearModel.1)~GDP.per.head) >> abline(devlm1) >> conflm1<-confint(devlm1) >> abline(coef=conflm1[,1],lty=2) >> abline(coef=conflm1[,2],lty=2) >> >> Jim >> >> >> >> On Wed, May 6, 2015 at 8:01 AM, varin sacha <varinsa...@yahoo.fr> wrote: >> > Hi, Dear R-helpers, >> > >> > Here below you will find a reproducible fictitious example working >> except the "abline" function. >> > >> > First thing : I try to draw the regression line (multiple linear >> regression). I try the "abline" function but it does not work. I don't get >> any error message but the straight line does not appear on the scatterplot. >> > >> > Second thing : I try to draw the 95% confidence intervals on the >> regression line. How could I do ? >> > >> > Using abline(0,1), I can of course add a line 45 degrees angle passing >> through the origin (intercept=0 and slope=1), but it is not what I am >> looking for. >> > >> > GDP.per.head=c(600,560,340,560,580,300,570,900,680,290,590,340) >> > Quality.score=c(4.5,6.5,6,4.5,7,3,9,10,12.5,6.5,7,9) >> > >> Competitivness.score=c(1000,1200,1400,700,680,1010,340,560,690,500,690,460) >> > LinearModel.1=lm(GDP.per.head ~ Quality.score + Competitivness.score) >> > plot(GDP.per.head, fitted(LinearModel.1)) >> > abline(GDP.per.head, fitted(LinearModel.1)) >> > >> > Thanks for your help. Looking forward to reading you. >> > >> > Sacha >> > >> > ______________________________________________ >> > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> > https://stat.ethz.ch/mailman/listinfo/r-help >> > PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html >> > and provide commented, minimal, self-contained, reproducible code. >> >> ______________________________________________ >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
